#include <iostream>
#include <deque>
template <typename T>
void print(const T &arr)
{
    for (auto it = arr.begin(); it != arr.end(); it++)
    {
        std::cout << *it << "\t";
    }
    std::cout << std::endl;
}
int main()

{
    std::deque<int> que;
    que.push_back(1);
    que.push_back(2);
    que.pop_front();
    print(que);
    return 0;
}